Quantum communication and quantum computation are two of the most important areas within the rapidly expanding and highly competitive field of quantum information science. They have attracted wide interest from physicists in many different subject areas because of their potential both for producing genuine quantum technologies and for providing a context for exploring many fundamental aspects of physics itself, such as entanglement and information capacity.
The pioneering scheme proposed by Knill, Laflamme and Milburn in 2001 made single-photon optics a legitimate candidate for producing a working quantum computer. While it would be brave to say that this scheme provides a practically feasible solution, it did stimulate an active theoretical effort in this direction and led to some of the earliest demonstrations of quantum logic gates. Moreover, since then, several major theoretical advances have provided very promising possibilities for achieving a genuinely scaleable photonic quantum computer.
A reliable source of heralded single photons would be a significant advance towards the goal of effective quantum computing.